1. Field of the Invention
The present invention relates to an image capturing apparatus having functions of continuous capturing and data compression, an image capturing control method, and a memory medium storing a program.
2. Description of the Related Art
A digital camera capable of setting a wide range of continuous capturing speed has recently been commercialized and become popular. In such kind of digital camera, image data obtained upon capturing is held anytime in a buffer memory, and image data is sequentially read from a buffer memory, compressed, and converted into a file based on Joint Photographic Experts Group (JPEG) or other standards, and recorded in a memory card or a memory medium.
For compression of image data, it is necessary to set the volume of compressed data under a predetermined value. If the compressed data volume is greater than a predetermined value, a process of retrying image data compression at a higher compression ratio is indispensable.
In such a field, a technology to estimate compression the volume of compressed image data without lowering a continuous capturing speed has been disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-064559, for example.
In the technology disclosed in this document, an image area used as a reference for estimating data volume is changed based on the total of time required to estimate data volume and time required to compress and convert image data into a data file.
Thus, as a continuous capturing speed is increased, an image area used as a reference for estimation is sequentially reduced, and the reliability of data volume estimation is decreased. Especially, at a higher continuous capturing speed, the volume of compressed data is estimated from a very small image area.
Therefore, actual compressed data volume is different from estimation, and may exceed a preset data volume, in such a case, a data compression process is retried, and the time required for data compression is consequently increased furthermore.
Generally, at a nigh continuous capturing speed, image data is sequentially obtained upon capturing and stored in a buffer memory, but compression of the stored image data is delayed, and a data compression process is continued even after the end of capturing. In such a case, a camera is under data processing unable to go to the next capturing, and increases the possibility of failing to release a shutter at a right moment.